From Atlas to ASP.NET AJAX, this nice development tool is finally released, and it is free. For ASP.NET developers, this is the time to seriously check it out. It is a huge enhancement to ASP.NET in Visual Studio 2005.
The official web site for this product: http://ajax.asp.net/default.aspx
Also check this blog for more behind scene information: http://weblogs.asp.net/scottgu/archive/2007/01/23/asp-net-ajax-1-0-released.aspx
(Scott is a Microsoft employee. His blog is one of the few I subscribe to. It has latest news about ASP.NET, IIS, and lots of tutorials.)